Device for introducing tools or instruments into an underwater well from a floating installation



June 23, 1970 P. JOUBERT ETAL 3,516,488

DEVICE FOR INTRODUCING TOOLS OR INSTRUMENTS INTO AN NDERWATER WELL FROMA FLOATING INSTALLATION Filed Dec. 26, 7 2 Sheets-Sheet l PHILIPPE TBERT and ANDRE CASTELA Wa M June 23, 1970 JOUBERT ETAL 3,516,488

DEVICE FOR INTRODUCING TOOLS 0R INSTRUMENTS INTO AN UNDERWATER WELL FROMA FLOATING INSTALLATION Filed D60. 26, 1967 2 Sheets-Sheet 2 PHILIPPETQUBERT and AN CASTELA m F; I QM ATTORNEY S United States Patent3,516,488 DEVICE FOR INTRODUCING TOOLS 0R INSTRU- MENTS INTO ANUNDERWATER WELL FROM A FLOATING INSTALLATION Philippe Joubert, Rungis,and Andr Castela, Mesnil-Le- Roi, France, assignors to Institut Francaisdu Petrole, des Carburants et Lubrifiants, Rueil-Malmaison, France FiledDec. 26, 1967, Ser. No. 693,584 Claims priority, applicatiozrgsFrance,Dec. 28, 1%6,

Int. Cl. E21b 337035; E21c 19/00 US. Cl. 166-5 7 Claims ABSTRACT OF THEDISCLOSURE The present invention relates to a device which permits theintroduction of servicing tools or measuring instiuments into anunderwater well provided with a submerged well-head, from a floatinginstallation, by suspending these tools or instruments by a flexibleline connected with the floating installation.

Prior to the present invention, there did not exist any device orapparatus permitting the performances of such an operation directly froma floating installation and it was necessary for the operators to divedown to the level of the well-head in order to place the servicingapparatus into position and make it work.

For working over well-heads located at depths which are inaccessible todivers, only attempts were made with submersibles provided withmanipulating arms controlled either from the interior of the submersibleor from the water surface, or also remotely controlled servicing devicesprovided with a lock for introducing tools into the well, whereby thewhole apparatus is laid onto the top of the well and must be raised eachtime the tool has to be changed.

A first object of the invention is to provide a device of theabove-mentioned type which is easy to use and capable of operatingdirectly from a floating installation such as a ship, without requiringthe use of an upwardly directed tubular extension of the well-head,known in the art as a riser.

Moreover, the adaptation of such a tubular extension to a producing oilwell having a submerged well-head, in order to introduce thereintoservicing tools or measuring instruments, comes up against problemsconcerning the design of the connections of the tubular element with thewell-head and with the floating installation, since these connectionsmust both have a suflicient resistance against the high pressure withinthe well and adapt themselves to the unavoidable movements of thefloating installation.

This problem is solved, according to the invention, with ice a servicingdevice for a submerged oil Well provided with a well-head, forintroducing into said well tools suspended by a flexible line from amobile surface installation. This device includes a flexible pipe forguiding .the lowering of said tools, said pipe connecting the wellheadwith the surface installation and being provided at its lower part withmeans for connecting said pipe with the top of the well-head, means forpermanently keeping under tension said pipe between the well-head andthe surface installation and two rigid bell-mouthed guiding devicessurrounding said pipe at respective locations respectively close to thewell-head and to the surface installation, said guiding devices limitingthe inclination which may be taken by said flexible pipe at saidlocations. These guiding devices consist of a downwardly widened upperguiding device carried by the surface installation and an upwardlywidened lower guiding device adapted to the top of said connectingmeans, the internal wall of said guiding device having in a section byan axial plane on incured profile whose slope, with respect to theguiding device axis, has a continuous variation.

; The flexible pipe of the device according to the invention can beeasily stored on the floating installation, rapidly handled and easilyconnected with the well-head by sliding along guide cables connectingthe floating installation with the well-head.

An embodiment of the invention will be hereinafter described, by way ofexample only, with reference to the attached drawings wherein:

FIG. 1 illustrates an overall view of the device according to theinvention,

FIG. 1a diagrammatically illustrates an embodiment of the flexible pipe.

FIGS. 2 and 3 show two different embodiments of the guarding devices ofthis device.

In FIG. 1, the reference numeral 1 designates elements such as aservicing tool (for example a tool for scraping the tubings of a well)or a measuring instrument which is intended to be introduced into asubmerged oil well.

These elements are introduced into the well through the well-head 2,from a floating installation 3 which is kept in position substantiallyabove the well, by means of any suitable anchoring or positioningsystem. The elements 1 are lowered at the lower part of a handling cable4 which is held in a point 5 on the floating installation, as by awinch, whose rotation is controllable and which may be locked, tomaintain the element 1 in a substantially stationary position.

The servicing device according to the invention includes a flexible pipe6, whose lower end is provided with a connector 7 for its connectionwith the top of 'the well-head. Means are provided for locking thisconnector on the well-head, these locking means being remotelycontrollable through a line 8a of the control cable or hose 8 connectedwith a control station 9 on the floating installation.

The control cable 8 may consist of several lines, such as lines 8a, 8band as shown in FIG. 1A, so as to permit, in particular, the controlfrom the station 9 of the opening or closing of the valves of thewell-head 2, such as master valve 31 and top valve 32 through lines 8band 8c of control cable 8 when the connector is connected with thelatter, particularly when the element 1 is to be introduced into thewell. The valve system (master 3 valves 31 and top valves 32) adapted tothe well-head may be of a conventional type and have therefore not beendiscribed.

The different lines 8a, 8b and 8c of the control cable 8 may be embeddedin the tubular core of pipe 6, as diagrammatically illustrated in FIG.1A.

The connector 7 is surmounted by a blow out preventer 13, which may beof a known type, adapted to withstand the pressure of the fluid insidethe oil well-head.

The connection of the connector 7 with the top of the well-head may beperformed in a known manner, using guiding elements such as the element10, adapted to guide this connector during the lowering thereof at thelower part of the pipe 6, by sliding along guide cables 11 and 12connecting the well-head with the floating installation.

At the upper end of the pipe 6 may be adapted a lock which a lock of aknown type may be adapted to permit elements to be introduced into thewell, such as the element 1, suspended by a cable which axiallytraverses the lock and is slidable therethrough for the lowering of theelements.

This lock is moreover not indispensable and may be substituted for by asimple stufling box 27 located at the upper part of a tube 26 and isadapted to the upper end of the pipe 6. The cable is slidable throughthis stufling box which provides for hydraulic tightness and isassociated with an outlet pipe 28 for the outlet of the excess of fluidunder pressure in the pipe 6 after the remotely controlled closing ofthe well-head valves and/or of the blow out preventer 13.

Rigid elements having the shape of incurved funnels with small angles ofaperture are adapted to the upper end of the pipe (element 24) and toits lower end (element 25), so maintain a sufficiently high radius ofcurvature of the flexible pipe to permit the introduction into the pipe(element 24) and into the well-head (element 25) of the servicingelements 1 of usual types lowered by means of the handling cable 4.

The replacement of the element 1 or the withdrawal thereof is effectedafter this element has been raised above the level of the connectingpoint 17 of the cable 16 and after the well-head valves and/or the blowout preventer 13 have been closed and the excess of pressure within thepipe 6 has been eliminated through the outlet pipe 28 and/or afterclosing the blow out preventer 29 which may optionally be adapted to thelower end of the tube 26.

The tube 26 or the lock located at this level will advantageously bedetachable so as to make easier the operations of connecting the element1 with the end of the cable 4 and of withdrawing this element.

A device which allows the element 1 suspended by a cable 4 to bemaintained, in an absolutely stationary position within the well,irrespective to the vertical movements (due to the waves, tides, etc.)which the floating installation is subjected to, includes a frame 14which is vertically movable along a guiding track or slide 15 and acable flexible line 16 having a connecting point at the upper part ofthe pipe 6 and a holding point 18 on the floating installation.

The frame 14 carries a first return pulley 19 for the cable 16 and asecond return pulley 20 for the cable 4 by which the element 1 issuspended. The return pulley 20 is movable with respect to the floatinginstallation since this pulley is carried by the frame 14.

This frame is subjected to the action of means for permanently keepingunder tension the cable 16 and the flexible pipe 6, this means beingconstituted in the illustrated embodiment by an hydraulic jack or ram 21connected through the pipe 22 with a source of hydraulic fluid (notshown), such as an oleo-pneumatic accumulator.

Under these conditions, the distance between the point 17 and thewell-head remains constant in spite of the displacements of the floatinginstallation. The position on the floating installation of the holdingpoint 18 for the cable 16 is so selected that the portion 16a of thiscable is perpendicular to the plane of the water-line of the floatinginstallation, i.e. is substantially vertical.

The cable 4 which supports the element 1 passes between the pulley 20and the holding point 5 (winch on which the cable is reeled) on asupplementary return pulley 23 the axis of which is integral with thefloating installation.

The position 01 tnls pulley 23 on the floating installation is soselected that the cable 4 between the pulleys 20 and 23 runs in adirection which is substantially perpendicular to the plane of thewater-line of the floating installation.

When the rotation of the winch 5 is blocked, this arrangement keeps theelement 1 at a fixed level inside the well.

Assuming that the floating installation 3 is vertically moved by thewaves over a height h, in either direction, with respect to the waterbottom; the frame 14 moves in the same direction by 11/2 With respect tothe water bottom, since the cable 16 and the flexible pipe 6 are keptunder tension between a connecting point 17, located at a constantdistance from the water bottom, and a holding point 18 which is integralwith the floating installation and thus displaced by h.

A displacement 11/2 results therefrom with respect to the water bottomof the return pulley 20 carried by the frame 14 and On which the cable 4passes and the pulley 23 integral with the floating installation issimultaneously displaced by h, with respect to the water bottom.

Consequently the distance between the element 1, and the water bottomremains unchanged, since the portion 4a of the cable 4 is parallel tothe direction of displacement and the length of the portion 4b of thecable 4 is invariable as long as the length of the cable 4 unreeled bythe winch 5 is unchanged.

The same process of automatic adjustment of the position of the pulleys19 and 20 permits the servicing element to be maintained at asubstantially constant distance of the well-head when the floatinginstallation is subjected to horizontal displacements of low amplitude.

These displacements cause an inclination of the flexible pipe 6 andhence a variation in the level of its end 17 which, as a result of theconstant length of the cable 16, results in a displacement of the pulley19 and of the frame 14 over a distance which is substantially equal toone half of the variation in the level of the end 17 with respect to thefloating installation.

The guiding devices 24, 25 according to the invention, two embodimentsof which being shown by way of nonlimitative examples by FIGS. 2 and 3,limit the radius of curvature taken by the flexible pipe 6, near theWater surface and the water bottom respectively under the action of thewater currents and of the unavoidable movements of the floatinginstallation. This radius of curvature is limited to a value which iscompatible both with the bending-resistance of the pipe 6 and with thenecessity to provide for a sufficient clearance between the internalwall of the pipe 6 and the extremities of each tool or instrument 1lowered into the well, or more precisely the extremities of each rigidelement of this tool or instrument (the most commonly used tools beingconstituted by several elements linked to each other), so as to avoidthe jamming of these tools or elements inside the flexible pipe, in thevicinity of the water bottom or of the water surface.

The guiding devices used according to the invention have a bell-mouthedshape differing substantially from the conical shape which could lead tothe break of the pipe at the level of the vertex of the cone, as aresult of the brutal variation at this level in the slope of theretaining surface which would be provided for the flexible pipe by aconical guiding device.

According to the invention, the internal wall of each guiding device 24and 25a has in section by an axial plane an incurved profile with a veryprogressive variation in the slope of this profile with respect to theguiding device axis, when the distance of this wall to said axisdecreases.

In order to make quite impossible any jamming of the tools orinstruments 1 at the level of the guiding devices, the radius ofcurvature R of the internal wall of these guiding devices will be at anypoint greater than the value R given by the formula:

R L2 2 d2) mm. d)

wherein D is the internal diameter of the flexible pipe 6, d the maximaldiameter of the tools introduced into the well through this pipe and 2Lthe length of the rigid part of the tool (length between twoswivel-joints in the case of a conventional tool consituted by asuccession of elements (la, lb, 10 linked to each other (FIG. 2).

With the types of flexible pipes and servicing tools available at thepresent time, the value of R will generally be between 5 and 20 metres,these values not, however, being limitative.

For example, for an inner diameter of the flexible pipe 6 equal to 70mm., the passage of an element having a length of 2 metres without anyswivel-joint requires a minimal radius of curvature of the internal wallof the guiding devices equal to 13 metres.

It will be possible for example, for the ease of fabrication, as in theembodiment shown by FIG. 2, to use guiding devices the internal walls ofwhich have in a section by an axial plane a profile with a constantradius of curvature R (profile of an arc of a circle).

The height h of the guiding device is limited on grounds of weight andoverall dimensions.

The angle of inclination of the pipe 6 with respect to the axis of theguiding device at the level of the widened rim thereof must be limited,by a suflicient traction on the pipe, to a value at least equal to theangle oz complying with the relation R sin u=h, at being the inclinationat this level of the tangent to the curve internally limiting thisguiding device in a section by an axial plane.

The tractive force acting on the pipe 6 is exerted by the hydraulic jack21 and depends in particular of the characteristics of the pipe 6, ofthe strength of the underwater currents and of the ratio 6/H, 6 beingthe maximal amplitude of the horizontal displacements of theinstallation with respect to the vertical of the well and H the waterdepth.

The 'tractive force to be exerted on the pipe 6 will generally be of theorder of a few tons to some tens of tons and it will be necessary toadmit angles of inclination of a few degrees for the pipe 6 in thevicinity of the water bottom and of the water surface respectively.

The angle of inclination of the pipe at the surface has a smaller valuethan that in the vicinity of the water bottom, as a result of the actionof the weight of this pipe (or more exactly of its apparent weight inthe water).

In FIG. 2, the tension applied to the pipe 6 is indicated by thereference T.

According to an advantageous embodiment of the guiding devices, shown byFIG. 3, the widened rim of the guiding device is extended by an incurvedflange 30 having a radius of curvature smaller than the value R i.e.insufficient for allowing the passage of the tools within the pipe *6 ifthe latter is applied against this flange as a result, for example, of acasual horizontal displacement of great amplitude of the floatingsurface installation. The value of the radius of curvature of the wallof this flange 30 is however at least equal to the minimal radius forwinding the pipe 6 (and for example equal to the radius of the winch onwhich this pipe is reeled on the floating surface installation) thusproviding for the pipe 6 a retaining surface which prevents this pipefrom breaking.

What is claimed is:

1. Device for working over a submerged well provided with a well-head,for introducing into said well tools suspended by a flexible line from amobile surface installa tion, said device including a flexible pipe forguiding said tools during the lowering thereof, said pipe connectingsaid well-head with said surface installation, and being provided at itslower end with means for connecting said pipe with said well-head, meansfor permanently keeping under tension said pipe between said well-headand said surface installation and two guiding bell-mounted devicessurrounding said flexibe pipe at locations respectively close to saidwell-head and to said surface installation, said devices limiting theinclinations taken by the pipe at said locations, said guiding devicescomprising a downwardly widening upper guiding device carried by saidsurface installation, and an upwardly widening lower guiding deviceadapted to the top of said connecting means, the internal wall of saidguiding devices having in a section by an axial plane an incurvedprofile the slope of which, relative to the guiding device axis, has acontinuous variation.

2. Device according to claim 1, wherein the widened rim of the lowerguiding device is provided with a safety flange whose wall which maycome into contact with said pipe has a radius of curvature smaller thanthe radius of the adjacent internal wall of said guiding device at thelevel of the widened flange thereof, but at least equal to the minimalradius necessary for reeling said flexible pipe.

3. Device for working over a submerged well provided with a well-head,for introducing into said well tools suspended by a flexible line from amobile surface installation, said device including a flexible pipe forguiding said tools during the lowering thereof, said pipe connectingsaid well-head with said surface installation, and being provided at itslower end with means for connecting said pipe with said well-head, meansfor permanently keeping under tension said pipe between said well-headand said surface installation and two guiding bell-mouthed devicessurrounding said flexible pipe at locations respectively close to saidwell-head and to said surface installation, said devices limiting theinclinations taken by the pipe at said locations, said guiding devicescomprising a downwardly widening upper guiding device carried by saidsurface installation, an upwardly widening lower guiding device adaptedto the top of said connecting means, the internal wall of said guidingdevices having in a section by an axial plane an incurved profile theslope of which, relative to the guiding device axis, has a continuousvariation and having in each point a radius of curvature greater than Dbeing the internal diameter of the flexible pipe, d the maximal diameterof the tools to be introduced into the well through said pipe and L halfthe length of the rigid part of said tools.

4. Device for working over a submerged oil well provided with aproduction well-head which includes a system of valves, for introducinginto said well tools suspended by a flexible line from a mobile surfaceinstallation, said device including a flexible pipe for guiding saidtools during the lowering thereof, said pipe connecting said well-headwith said surface installation, and being provided at its lower end withmeans for connecting said pipe with said well-head, means forpermanently keeping under tension said pipe between said well-head andsaid surface installation and two guiding bell-mouthed devicessurrounding said flexible pipe at locations respectively close to saidwell-head and to said surface installation, said devices limiting theinclinations taken by the pipe at said locations, said guiding devicescomprising a downwardly widening upper guiding device carried by saidsurface installation, and an upwardly widening lower guiding deviceadapted to the top of said connecting means, the internal wall of saidguiding devices having in a section by an axial plane an incurvedprofile the slope of which, relative to the guiding device axis, has acontinuous variation, said flexible pipe being adapted to withstand thepressure inside said Well and including at its lower part a connectorwhich is connected to the surface installation by a line for remotecontrol and provides both for the hydraulic connection with thewell-head and for the connection of the wellhead valves with said remotecontrol line, said line being provided with a blow-out preventer at oneof its ends and being provided at its upper part with means forintroducing said tools into said flexible pipe, said means beingprovided at their upper part with sealing means allowing the freesliding of said flexible line by which said tool is suspended.

5. Device according to claim 4, wherein said flexible pipe is providedat its lower part with a blowout preventer connected With said surfaceinstallation by a line for remote control.

6. Device according to claim 4, wherein conductors for remote controlare incorporated in said flexible pipe.

7. Device according to claim 4, wherein a blowout preventer is locatedat the upper part of said flexible pipe, at a level which is lower thanthat of said sealing means.

References Cited UNITED STATES PATENTS 3,142,343 7/1964 Otteman et al1757 3,142,344 7/1964 Otteman et a1. 175-7 3,276,746 10/1966 Berne l-5 X3,277,969 10/1966 Vincent l755 3,336,975 8/1967 Word 166.5 3,367,4212/1968 Raulins 166.5 3,378,067 4/1968 Leonard et a1. 166-.5

NILE C. BYERS, JR., Primary Examiner R. E. FAVREAU, Assistant ExaminerU.S. Cl. X.R. -7

